Facsimile optical scanning apparatus



Sept. 3%, 195 A. NYMAN FACSIMILE OPTICAL SCANNING APPARATUS 3Sheets-Sheet 1 Original Filed Aug. 4, 195] mum Sept. 30, m8 A. NYMAN2,854,509

FACSIMILE OPTICAL SCANNING APPARATUS Original Filed Aug. 4, 1951 3Sheets-Sheet 2 v jficzazzder A zn an rjiwm Wei '51s.

Sept. 36, 1958 A. NYMAN 2,854,509

FACSIMILE OPTICAL SCANNING APPARATUS Original Filed Aug. 4, 195] 3Sheets-Sheet 3 .12? KS 2% kw United States Patent FACSMILE OPTICALSCANNING APPARATUS Alexander Nyman, Dover, Mass., assignor to AldenProducts Co., Brockton, Mass, a corporation of Massachusetts Originalapplication August 4, 1951, Serial No. 240,418. Divided and thisapplication February 12, 1953, Serial No. 336,499

3 Claims. (Cl. 178--7.6)

This invention relates to an optical system for directing the course oflight from one location to another and more particularly to apparatusfor scanning a sheet of indicia or other subject copy.

Objects of the invention are to provide optical apparatus which directslight from one course to another without the loss of much of the lightand to provide such apparatus which is compact and can be encompassed ina restricted space.

In one aspect the present invention involves a light conductor in theform of a plate of light conducting material having a high index ofrefraction, the plate having a light-entering edge to receive light, alightemerging edge angularly related to the light-entering edge, and anintermediate elliptical reflecting edge. In the preferred embodiment theplate is folded and the radius of curvature of the fold is such that theangle of incidence of the internally-reflected light exceeds thecritical angle of the material.

In a more specific aspect the invention involves optical scanningapparatus comprising a light-sensitive device responsive to variationsin light intensity, together with means for scanning the copy point bypoint including a lens for focusing the scanning light of the device anda plate of light conducting material having a high index of refraction,the plate having a light-entering edge facing the lens to receive thelight focused thereby, a lightemerging edge angularly related to thelight-entering edge and an intermediate elliptical reflecting edgehaving one focus at the lens and the other focus at the device.

In a still more specific aspect of the invention the optical systemincludes a drum having a helically shaped aperture and a plate having alinear aperture arranged parallel to the axis of the drum adjacent theperiphery thereof, the aforesaid apertures being interposed in theoptical path of the light rays between the copy and the light-sensitivedevice, and means for rotating the drum so that selected elemental areasof the copy whose dimensions are determined by the apertures aresuccessively imaged upon the device, the aforesaid plate being disposedwithin the drum with its light-entering edge facing said linear apertureand its light-emerging edge facing one end of the drum and the aforesaiddevice being located outside said end of the drum.

For the purpose of illustration a typical embodiment of the invention isshown in the accompanying drawings in which,

Fig. 1 is a side elevation view with portions broken away of a preferredembodiment of an optical scanner;

Fig. 2 is a sectional. view on line 22 of Fig. 1;

Fig. 3 is a fragmentary isometric view showing the relationship of thephotoelectric cell and the light conductor;

Fig. 4 is a developed view of the light conductor;

Fig. 5 is a side view of the light conductor, and

Fig. 6 is a fragmentary end view of the light conductor.

As is best shown in Figs. 1 and 3 the embodiment of Patented Sept. 30,1958 ice from the rear of the base. The bracket 24 has bosses 26positioned at either end thereof wherein are carried respectively twovertically disposed columns 28 which telescope in apertures in thebosses being secured in adjusted position by means of thumb screws 30.

Upon the upper ends of the columns 28 is carried a copy table 32, whichhas an upper copy guiding surface 34, each side of which is reinforcedby a respective rib 36. At the rear end of each rib 36 is an integrallycast finger or tab 40 which is turned inwardly and provided with anaperture for engaging the upper end of a respective column 28. The table32 is held in position by two pairs of nuts 42 and 44 which engagethreads cut in the ends of the columns 28 so that nuts are positionedrespectively above and below ,the tabs 40. As is shown in Fig. 2, thesurface 34 of the copy table 32 is provided with a transverse slot A andis brightly illuminated from the bottom of the table by light from twotubular electric lamps L (Fig. 2) preferably of the fluorescent type.The lamps L are enclosed in a lamp housing 45 which is suspended beneaththe table 32. A slotted aperture A is positioned at the apex of theenclosed legs where it is in vertical alignment with the table apertureA.

As the sheet of subject copy is moved over the illuminated aperture A,the image thereof is reflected by a stationary mirror 92 (Fig. 2)pivotally mounted in a bracket 94 which is attached to the base 20 bymeans of cap screws 96. The relative position of the mirror isadjustable by means of a screw 98, which operates against the biasingforce exerted by a spring 99 so that the light rays from the aperture Aare directed through a converging lens system 100 which is also mountedin the bracket 94.

The converging lens system 100, which is of conventional design, focusesthe light rays upon two aperture members which define the dimensions ofthe scanning spot as will appear hereinafter. The first aperture memberis linear comprising a plate 102 having a horizontally disposedelongated slot. Cemented or otherwise secured to the rear face of theplate 102 is an opaque.

photographic film 104, whereupon is developed a transparent straightline having a width of approximately 0.002 inch, which being locatedadjacent the slot in the plate defines an elongated optical aperture.The aperture plate 102 is held in two grooved guides 106 which areattached respectively to two end Walls 108 and 109 of a housingdesignated generally by the numeral 110.

The housing 110 is closed by a sheet metal cover 113 and secured to thebase 20 by means of screws 112. Cast as an integral portion of thehousing 110 is base plate 114 (Fig. 1) whereupon is secured a cast cover116 by means of screws (not shown). Enclosed within the cover 116 is aphotoelectric cell such as the phototube P whose function will bedescribed in detail hereinafter.

A second aperture, helical in shape, is developed as a 0.003 line uponan opaque photographic film 120 which is arranged about the periphery ofa cylindrical aperture member such as the drum 122 (Fig. 2) of atransparent material such as glass or a suitable plastic. One end of thedrum 122 is supported by a head 124 having a cylindrical portion with aplurality of axially disposed slots which permit the cylindrical portionto be inserted within the end of the drum with a snug fit. Thecylindrical portion has an integral shaft, which engages the inner raceof a ball bearing 126 (Fig. 1). The outer race of the bearing 126 fitsin a recess in a retaining plate 128 which is secured to the housing end108 by means of screws 130. The plate 128 also supports a driving motorMd for the drum 122, the motor shaft engaging a recess in the end of thedrum shaft supported by the hearing 126. Relative movement between theshafts is prevented by means of a set screw 132.

The oppositeend of the drum 122 is supportedby a sleeve 134 which isprovided with a plurality of axial slots so that it can be slipped overthe outside of the drum. The outer surface of the sleeve 134 is groundto fit the inner race of a large ball bearing 136 whose outer race isseated in a recess in the housing end 109.

The bearings 1'26 and 136 are located so that the axis of rotation ofthe drum 122 is in the horizontal plane which passes through the linearaperture of the plate 102 and the optical axis. of the lens system 100.As the drum 122 is rotated by the motor Md, the helical aperture carriedthereby moves behind the linear aperture in a lengthwise direction sothat light from sequentially exposed elemental areas of the transverseelement of the subject copy exposed by the longitudinal slot A in thecopy table surface 34 are admitted to the interior of the drum, i. e.,the linear and helical apertures define the dimensions of a scanningspot which is moved acrossthe copy.

To prevent the loss of definition the clearance between the helical andlinear apertures is minimized by positioning the aperture defining films120 and 104 respectively upon the outer surface of the drum 122, and theback or inner face of the plate 102, as has been described heretofore,it is possible to reduce this clearance to approximately 0.004 inch.

To permit the mounting of the photoelectric tube P outside the drum 122and the use of a longer linear aperture, the light rays are directedthrough a light conductor 1400f a sheet material, such as methylmethacrylate resin having a high index of refraction. The shape of thelight conductor 140 is best shown in Figs. 3, 4 and 5, wherein 142 and144 designaterespectively the light entering and emerging edges thereof.A third edge 146 is in the form of'a reflecting surface generated, forexample by moving a linear element along a concave curve such as anellipse. To increase the reflecting properties of the elliptical edge146 it is lacquered and a brilliant reflecting surface of silverdeposited thereupon.

The operation of the light conductor will be more apparent fromaconsideration of Fig. 4 wherein is shown a" development of theconductor and one of the foci F of the elliptical edge 146. It will beapparent from the geometry of the figure that light rays from an objectplaced at the other focus of the ellipse, which is not shown, will enterthe edge 142, be reflected by the elliptical edge 146, and emerge fromthe edge 144 to form an image at the focus F. Further, when the lightconductor 140 is folded about an axis substantially parallel to theentering edge 142 as shown in Figs. 5 and 6,

with the radius of curvature of the bent portion made great enough sothat the angle of incidence of the light rays exceeds the critical angleof the material, light rays from an object located at a positioncorresponding. to the position of the focus of the ellipse after thebending of the light conductor will continue to be reflected to form animage at the focus F. From the above it follows thatby proportioning theaxis of the ellipse and the bend in the light'conductor 140 so that thelens 100and the collector electrode-of. the photoelectric tube P arelocated at the respectivefoci, any light emerging from the straps-bymeansfof screws-r152. As is best shownin" Fig: 6;-the"straps'148=and 150are bent back to attach to a ring 154 by means of screws 156. The ring154 is provided with several offset tabs which are attached to thehousing end 109 by means of screws 158 so that the end of the lightconductor projects into the drum 122 with its entering edge 142 oppositethe linear aperture in the plate 102 and its emerging edge adjacent thephotoelectric tube P.

Scanning is accomplished by moving the copy over the table surface 34past the elongated slot A by means of the two pair of rolls 56 and 62which are operated by the motor M, as was described heretofore, so thatsuccessive transverse elements of the copy are exposed through the slot.The light rays from the lamps L brightly illuminate the element of thecopy appearing at the slot so that it is imaged upon the slot in linearaperture plate 102 by the mirror 92. The drum 122 shields the lightconductor 140 from the reflected light rays except for those forming asmall spot passing through the helical slot in the drum to impinge uponthe entering edge 142 ofthe light conductor 1'40 whereby the rays' aredirected to the collector electrode of the photoelectric tube P ash'asbeen described in detail heretofore. Rotation of the drum 122results in the equivalent of the movement of the spot of light acrossthe entering edge 1420f the light conductor as the helical slot rotatesso that the photelectric tube P seesf successive elemental area of thesubject copy exposed by the slot A. By correlating the rate of advanceof the copy with the speed of rotation of the drum 122, sequential alonga line including a lens for focusing an image of the, scanned line in aplane between the copy and said device and a plate of light-conductingmaterial having a high index of refraction, the plate having alight-entering edge facing said lens to receive the light from the line'image focused thereby, a light-emerging edge angularly' related to thelight-entering edge and an intermediate elliptical reflecting edgehaving one focus at said lens and the other focus at said device, saidplate being folded and the radius of curvature of the fold being suchthat the angle of incidence of the internally-reflected light exceedsthe critical angle of the material, whereby light from said line imageis uniformly collected on said device substantiallywithout loss.

2. Optical scanning apparatus for a subject copycomprising alight-sensitive device responsive to variations in light intensity, alens for focusing light rays from an element of the copy on an imageplane, said system including a drum having a helically shaped apertureand a plate having a linear aperture arranged parallel to the axis ofthe drum adjacent the periphery thereof, said apertures being interposedin the optical path of the light rays between the copy and thelight-sensitive device substantially in said image plane, and means forrotatingthe drum so that selected elemental areas of the copywhosedimensions are determined by the apertures are successivelytransmitted to the device, and in said drum a plate of light-conductingmaterial having a high index of refraction, the plate having alight-entering edge juxtaposed to and facing said linear aperture, alight-emerging'edge,

facing one end of the drum and an intermediate elliptical reflectingedge having one focus at said lens and the other focus at said device,said device being located outside said end of the drum, said plate beingfolded for insertion in the drum, and the radius of curvature of thefold being such that the angle of incidence of the internally-reflectedlight exceeds the critical angle of the material whereby lighttransmitted from said lens through said linear aperture is uniformlycollected on said device substantially without loss.

3. For collecting light from a linear light source a light conductorcomprising a plate of light conducting material having a relatively highindex of refraction, one edge of said plate forming a curve having twofoci, two other edges of said plate being polished to form asubstantially recilinear light-entering edge, said two edges beingdisposed between said curvilinear edge and said foci respectively, andsaid plate being folded about an axis extending substantially parallelto one of said two edges whereby light from one of said foci entering atpoints along said entering edge is reflected by said curvilinear edgeout the 15 2,770,712

other edge and collected at the other of said foci substantially withoutloss.

References Cited in the file of this patent UNITED STATES PATENTS1,762,383 Booraem June 10, 1930 1,976,270 Urfer Oct. 9, 1934 2,287,605Dickson June 23, 1942 2,376,448 Neugass May 22, 1945 2,404,627 GoldbergJuly 23, 1946 2,510,200 Thompson June 6, 1950 2,514,619 Anderson July11, 1950 2,639,322 Young May 19, 1953 Dros Nov. 13, 1956

